Viewing this clip, I am reminded of other musicals where the future relationship between characters is 'foreshadowed' in a song ('Only Make Believe' from Showboat, 'If I Loved You' from Carousel, etc.) It's obvious that there's a romantic attraction, but it's too early in the film/show or the 'slow burn' is intentional for dramatic effect when the relationship is finally allowed to bloom. These two are obviously 'into' each other, or at the least, very intrigued by that notion. The flirtatious banter and eye contact are impossible to ignore. He is hardly shy about stating his interest in her, even inquiring about the 'competition' he's facing from another suitor. She is much more coy about her interest, which is very typical (or stereotypical) behavior from a leading lady of the time.
I've not seen either performer in a film before, but I am definitely aware of their names and reputations. I grew up with parents who adored Nelson Eddy's singing, and we had many of his records in our vast collection of vinyl. His vocal range was impressive, to say the least.
The interactions between the two leads is socially appropriate under the code, reflecting the expectation that the man will act as a gentleman and the lady will be polite, demure, and 'lady-like' in her actions.
